Tracking Control of Robotic Manipulators based on the All-Coefficient Adaptive Control Method

Yongjun Lei,Hongxin Wu 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.2

A multi-variable Golden-Section adaptive controller is proposed for the tracking control of robotic manipulators with unknown dynamics. With a small sample time, the unknown dynamics of the robotic manipulator are denoted equivalently by a characteristic model of a 2-order multi variable time-varying difference equation. The coefficients of the characteristic model change slowly with time and some of their valuable characteristic relationships emerge. Based on the characteristic model, an adaptive algorithm with a simple form for the control of robotic manipulators is presented, which combines the multi-variable Golden-Section adaptive control law with the weighted least squares estimation method. Moreover, a compensation neural network law is incorporated into the designed controller to reduce the influence of the coefficients estimation error on the control performance. The results of the simulations indicate that the developed control scheme is effective in robotic manipulator control.

Investigation on pulse electrochemical machining by coated electrode

Wu Ming,Zhongning Guo,Yongjun Tang,Guan Wang,Taotao Sun,Shuzhen Jiang 한국생산제조학회 2014 한국생산제조시스템학회 학술발표대회 논문집 Vol.2014 No.9(2)

Correlation between Vitamin B12 and Mental Health in Children and Adolescents: A Systematic Review and Meta-analysis

Yongjun Tan,Li Zhou,Kaiqi Gu,Caihong Xie,Yuhan Wang,Lijun Cha,Youlin Wu,Jiani Wang,Xiaosong Song,Xia Chen,Hua Hu,Qin Yang 대한정신약물학회 2023 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.21 No.4

To conduct the association between vitamin B12 and mental health in children and adolescents. Five databases were searched for observational studies in any language reporting on mental health and vitamin B12 levels or intake in children and adolescents from inception to March 18, 2022. Two authors independently extracted data and assessed study quality. Qualitative and quantitative analysis of data were performed. The review was registered in the PROSPERO database (CRD42022345476). Fifty six studies containing 37,932 participants were identified in the review. Vitamin B12 levels were lower in participants with autism spectrum disorders (ASD) (standardized mean difference [SMD], −1.61; 95% confidence interval [95% CI], −2.44 to −0.79; p < 0.001), attention deficit hyperactivity disorders (SMD, −0.39; 95% CI, −0.78 to −0.00; p = 0.049) compared with control group. Vitamin B12 intake were lower in participants with ASDs (SMD, −0.86; 95% CI, −1.48 to −0.24; p = 0.006) compared with control group, but showed no difference between depression group (SMD, −0.06; 95% CI, −0.15 to 0.03; p = 0.17) and the control group. Higher vitamin B12 intake were associated with lower risk of depression (odds ratio [OR], 0.79; 95% CI, 0.63−0.98; p = 0.034) and behavioral problems (OR, 0.83; 95% CI, 0.69−0.99; p = 0.04). The vast majority of included studies supported potential positive influence of vitamin B12 on mental health, and vitamin B12 deficiency may be a reversible cause for some mental health disorders in children and adolescents.

Lightweight Design of an Automotive Battery-Pack Enclosure via Advanced High-Strength Steels and Size Optimization

Pan Yongjun,Xiong Yue,Wu Lei,Diao Keshan,Guo Wei 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5

The battery packs are crucial components of electric vehicles and may severely affect the continue voyage course and vehicle safety. Therefore, design optimization of the battery-pack enclosure (BPE) is critical for enhanced mechanical and crashwrothiness performances. In this study, a lightweight design of an automotive BPE under the loading conditions is presented based on the advanced high-strength steels (AHSSs) and size optimization. A numerical analysis procedure is also introduced for the lightweight design. First of all, a nonlinear finite element (FE) BPE model was established and validated through the modal test. Secondly, the random vibration simulation was performed based on the sensitivity analysis to initially determine the AHSSs and thickness for the components of the BPE. Next, the material and thickness were determined by the fixed frequency vibration analysis. Moreover, the mechanical shock and fatigue life were analyzed numerically. Finally, the crashworthiness of the optimized BPE model was verified by crash and crush simulations. The results show that the optimized BPE structure has a 10.41 % lightweight gain, while assuring enhanced dynamic performances. The introduced numerical procedure could be used to quickly determine the material and thickness of each component of BPE. The design optimization process was found beneficial to reduce the number of physical tests and product development cost and shorten product development cycles.

셀룰러 망의 이동국 속도와 방향을 이용한 핸드오프율 계산법

우매리(Mari Wu),최용준(YongJun Choi),정영석(Youngseok Jung),임경수(KyungSoo Lim),김종근(Chonggun Kim) 한국정보과학회 2002 정보과학회논문지 : 정보통신 Vol.29 No.4

CDMA셀룰러 시스템에서는 이동국이 한 셀에서 다른 셀로 이동할 때에 핸드오프영역에서 인접한 양 셀의 채널을 신호를 동시에 점유함으로써 끊김 없는 연결을 가능하게 한다. 이 경우에 핸드오프 영역에 있는 이동국은 현재 셀의 신호 수신 지역을 벗어나지 않아도 양 기지국와 연결을 유지하는데 이것은 채널 효율성에 낭비를 가져온다. 따라서 핸드오프 율은 채널 효율성을 평가하는 중요한 요소이다. 본 논문에서는 CDMA셀룰러 시스템에서 이동국의 이동 속도와 방향을 기반으로 핸드오프 확률과 핸드오프 호수를 구하는 방식을 제안하였다. In CDMA cellular systems, a handoff process in which the mobile station (MS) can communicate with the target base station without interrupting the communication with the current base station makes contact with the target base station before it breaks with the station it is operating on. An MS requests a soft handoff to a neighbor base station (BS) whenever the pilot strength received from the neighbor BS exceeds the handoff threshold, even though the MS may not actually be approaching to the neighbor BS. Since two traffic channels have to assign to an MS during the soft handoff period, the utilization of traffic channels is wasted. Thus, an analysis of handoff rate is a key to understand and evaluate channel efficiency. In this paper, a simple and straightforward mathematical analysis method for evaluate obtaining direction-based soft handoff rate and the number of handoff calls in CDMA cellular systems is proposed.

miR-133a-3p and miR-145-5p co-promote goat hair follicle stem cell differentiation by regulating NANOG and SOX9 expression

Wang Jian,Wu Xi,Zhang Liuming,Wang Qiang,Sun Xiaomei,Ji Dejun,Li Yongjun 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.4

Objective: Hair follicle stem cells (HFSCs) differentiation is a critical physiological progress in skin hair follicle (HF) formation. Goat HFSCs differentiation is one of the essential processes of superior-quality brush hair (SQBH) synthesis. However, knowledge regarding the functions and roles of miR-133a-3p and miR-145-5p in differentiated goat HFSCs is limited. Methods: To examine the significance of chi-miR-133a-3p and chi-miR-145-5p in differentiated HFSCs, overexpression and knockdown experiments of miR-133a-3p and miR145-5p (Mimics and Inhibitors) separately or combined were performed. NANOG, SOX9, and stem cell differentiated markers (β-catenin, C-myc, Keratin 6 [KRT6]) expression levels were detected and analyzed by using real-time quantitative polymerase chain reaction, western blotting, and immunofluorescence assays in differentiated goat HFSCs. Results: miR-133a-3p and miR-145-5p inhibit NANOG (a gene recognized in keeping and maintaining the totipotency of embryonic stem cells) expression and promote SOX9 (an important stem cell transcription factor) expression in differentiated stem cells. Functional studies showed that miR-133a-3p and miR-145-5p individually or together overexpression can facilitate goat HFSCs differentiation, whereas suppressing miR-133a-3p and miR-145- 5p or both inhibiting can inhibit goat HFSCs differentiation. Conclusion: These findings could more completely explain the modulatory function of miR-133a-3p and miR-145-5p in goat HFSCs growth, which also provide more understandings for further investigating goat hair follicle development.

Estimation of Electromechanical Modes from Ambient PMU Data in China Southern Power Grid

Shi, Bonian,Wu, Jingtao,Yang, Dong,Liu, Yongjun The Korean Institute of Electrical Engineers 2013 The Journal of International Council on Electrical Vol.3 No.3

Online estimation of electromechanical oscillation modes using ambient PMU data is adopted for monitoring the China Southern Power Grid (CSG). After some preprocessing steps, the ambient PMU data is processed by ARMA (Autoregressive Moving average) method, different identification results are obtained from multiple PMU sites. Then by utilization of a clustering method, oscillation modes representing the system operating conditions are derived. In this paper, we report on the preliminary results in CSG and restriction on the ambient data usage is explained. Application of ambient data analysis for oscillation event study is also proposed to judge the oscillation type by comparing the estimated damping ratio value before and during ringdown period. Some suggestions on further ambient data analysis study are also discussed.

Experiment on the Behavior of a Self-Anchored Suspension and Cable-Stayed Hybrid Bridge during Structural Transformation

Yu Zhao,Yongjun Zhou,Lingling Wu,Changchang Li,Zhongguo John Ma 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

The Longgang Bridge in Shaanxi, China, is a complex continuous hybrid structure composed of two cable-stayed self-anchored suspension parts and one single-pylon cable-stayed part. A 1:20-scaled model was established due to the effect of multiple structural transformation, frequent internal force changes during the construction process, and differences between actual material parameters and theoretical calculation parameters. In this paper, the design, materials, counterweight, experimental instrumentation, and construction stages of the scaled model are introduced. Based on the experimental data, the nonlinear behavior of the self-anchored suspension and cable-stayed hybrid bridge during the structural transformation of the construction process is systematically and comprehensively studied. The evolutions of the hanger force and stayed cable force, the variation in the subcable and back-cable forces, the displacement characteristics of the suspension cable and the deflection of the stiffened girder are analyzed, and the relationships among these variables in different states of the structural system are discussed. This paper will serve as a technical reference for the construction of similar bridges in the future.

Transfer function modeling of structural vibration of complex aerospace structures based on finite element analysis

Xin Feng Wu,Yongjun Lei,Daokui Li,Yan Xie 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

An approach to establish the transfer function of complex aerospace structures to express their structural vibration behavior through finite element modeling is proposed. The fundamental idea of the approach is to characterize the vibrations of complicated structures through the transfer function model for an advanced control system design, while the parameters of the model are identified from the response data obtained through finite element analysis. The proposed method comprises four steps, namely, finite element modeling and validation, data preparation based on the finite element analysis, parameter identification of the transfer function, and model validation,and is presented from both frequency and time domains. The developed approach is applied to a cantilever beam, a strap-on launch vehicle,and a local part of the aerospace structure to demonstrate the method’s effectiveness and satisfactory performance.

Effect of additives on structure and corrosion resistance of ceramic coatings on Mg–Li alloy by micro-arc oxidation

Shi Lingling,Xu Yongjun,Li Kang,Yao Zhongping,Wu Songquan 한국물리학회 2010 Current Applied Physics Vol.10 No.3

In order to improve the corrosion resistance of ceramic coatings formed on Mg–5mass%Li substrate by micro-arc oxidation (MAO) method, two kinds of additives (Na2B4O7 and EDTA) were doped in Na2SiO3–Na3PO4 solution system. The surface and cross-section morphology feature, phase composition and elemental composition were examined by SEM, XRD and EDX, respectively. Corrosion resistance of ceramic coating was tested by electrochemical methods. It was revealed that all coatings were composed of MgO and Mg2SiO4, and had porous surface structure. Doping of additives had little effect on the elemental composition, while it influenced the morphological feature of the coating. The results of electrochemical tests showed that the coatings prepared in the solutions with additive had good corrosion resistance. The addition of EDTA to the solution made coatings thinner and more uniform which resulted in better general corrosion resistance. The addition of Na2B4O7 to the solution made coatings much thicker and compacter, which improved the pitting corrosion resistance.